Fix missed exception spec checks and crashes

Delayed exception specification checking for defaulted members and virtual
destructors are both susceptible to mutation during iteration so we need to
process the worklists fully.

This resolves both accepts-invalid and rejects-valid issues and moreover fixes
potential invalid memory access as the contents of the vectors change during
iteration and recursive template instantiation.

This patch also adds two assertions at end of TU to ensure no specs are left
unchecked as was happenning before the fix, plus a test case from Marshall Clow
for the defaulted member crash extracted from the libcxx headers.

Reviewed by Richard Smith.

llvm-svn: 192914

clang/include/clang/Sema/Sema.h

@@ -4789,7 +4789,7 @@ public:
   void CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD);
   void CheckExplicitlyDefaultedMemberExceptionSpec(CXXMethodDecl *MD,
                                                    const FunctionProtoType *T);
-  void CheckDelayedExplicitlyDefaultedMemberExceptionSpecs();
+  void CheckDelayedMemberExceptionSpecs();
 
   //===--------------------------------------------------------------------===//
   // C++ Derived Classes

clang/lib/Sema/Sema.cpp

@@ -792,6 +792,11 @@ void Sema::ActOnEndOfTranslationUnit() {
     }
   }
 
+  // All delayed member exception specs should be checked or we end up accepting
+  // incompatible declarations.
+  assert(DelayedDefaultedMemberExceptionSpecs.empty());
+  assert(DelayedDestructorExceptionSpecChecks.empty());
+
   // Check we've noticed that we're no longer parsing the initializer for every
   // variable. If we miss cases, then at best we have a performance issue and
   // at worst a rejects-valid bug.

clang/lib/Sema/SemaDeclCXX.cpp

@@ -4864,14 +4864,27 @@ void Sema::CheckExplicitlyDefaultedMemberExceptionSpec(
     SpecifiedType, MD->getLocation());
 }
 
-void Sema::CheckDelayedExplicitlyDefaultedMemberExceptionSpecs() {
-  for (unsigned I = 0, N = DelayedDefaultedMemberExceptionSpecs.size();
-       I != N; ++I)
-    CheckExplicitlyDefaultedMemberExceptionSpec(
-      DelayedDefaultedMemberExceptionSpecs[I].first,
-      DelayedDefaultedMemberExceptionSpecs[I].second);
+void Sema::CheckDelayedMemberExceptionSpecs() {
+  // Perform any deferred checking of exception specifications for virtual
+  // destructors.
+  while (!DelayedDestructorExceptionSpecChecks.empty()) {
+    std::pair<const CXXDestructorDecl *, const CXXDestructorDecl *> Check =
+        DelayedDestructorExceptionSpecChecks.pop_back_val();
+    const CXXDestructorDecl *Dtor = Check.first;
+    assert(!Dtor->getParent()->isDependentType() &&
+           "Should not ever add destructors of templates into the list.");
+    CheckOverridingFunctionExceptionSpec(Dtor, Check.second);
+  }
 
-  DelayedDefaultedMemberExceptionSpecs.clear();
+  // Check that any explicitly-defaulted methods have exception specifications
+  // compatible with their implicit exception specifications.
+  while (!DelayedDefaultedMemberExceptionSpecs.empty()) {
+    std::pair<CXXMethodDecl *, const FunctionProtoType *> Spec =
+        DelayedDefaultedMemberExceptionSpecs.pop_back_val();
+    CheckExplicitlyDefaultedMemberExceptionSpec(Spec.first, Spec.second);
+  }
+
+  assert(DelayedDestructorExceptionSpecChecks.empty());
 }
 
 namespace {
@@ -8182,9 +8195,8 @@ void Sema::DefineImplicitDefaultConstructor(SourceLocation CurrentLocation,
 }
 
 void Sema::ActOnFinishDelayedMemberInitializers(Decl *D) {
-  // Check that any explicitly-defaulted methods have exception specifications
-  // compatible with their implicit exception specifications.
-  CheckDelayedExplicitlyDefaultedMemberExceptionSpecs();
+  // Perform any delayed checks on exception specifications.
+  CheckDelayedMemberExceptionSpecs();
 
   // Once all the member initializers are processed, perform checks to see if
   // any unintialized use is happeneing.
@@ -8707,23 +8719,11 @@ void Sema::ActOnFinishCXXMemberDecls() {
   // If the context is an invalid C++ class, just suppress these checks.
   if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(CurContext)) {
     if (Record->isInvalidDecl()) {
+      DelayedDefaultedMemberExceptionSpecs.clear();
       DelayedDestructorExceptionSpecChecks.clear();
       return;
     }
   }
-
-  // Perform any deferred checking of exception specifications for virtual
-  // destructors.
-  for (unsigned i = 0, e = DelayedDestructorExceptionSpecChecks.size();
-       i != e; ++i) {
-    const CXXDestructorDecl *Dtor =
-        DelayedDestructorExceptionSpecChecks[i].first;
-    assert(!Dtor->getParent()->isDependentType() &&
-           "Should not ever add destructors of templates into the list.");
-    CheckOverridingFunctionExceptionSpec(Dtor,
-        DelayedDestructorExceptionSpecChecks[i].second);
-  }
-  DelayedDestructorExceptionSpecChecks.clear();
 }
 
 void Sema::AdjustDestructorExceptionSpec(CXXRecordDecl *ClassDecl,

clang/test/SemaTemplate/exception-spec-crash.cpp

@@ -0,0 +1,30 @@
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++11 -fcxx-exceptions -DCXX_EXCEPTIONS -fsyntax-only -verify %s
+
+template <class _Tp> struct is_nothrow_move_constructible {
+  static const bool value = false;
+};
+
+template <class _Tp>
+class allocator;
+
+template <>
+class allocator<char> {};
+
+template <class _Allocator>
+class basic_string {
+  typedef _Allocator allocator_type;
+  basic_string(basic_string &&__str)
+  noexcept(is_nothrow_move_constructible<allocator_type>::value);
+};
+
+class Foo {
+  Foo(Foo &&) noexcept = default;
+#ifdef CXX_EXCEPTIONS
+// expected-error@-2 {{does not match the calculated}}
+#else
+// expected-no-diagnostics
+#endif
+  Foo &operator=(Foo &&) noexcept = default;
+  basic_string<allocator<char> > vectorFoo_;
+};